Exam #5: Review Flashcards Preview

Biochemistry > Exam #5: Review > Flashcards

Flashcards in Exam #5: Review Deck (33):
1

Allele Heterogeneity

- Different mutations in the same gene cause different phenotypes
- Beta-Thalassemia

2

Locus Heterogeneity

- Mutations in different genes cause the same phenotype
- Albinism

3

Modifier Genes

The individual genetic background modifies the phenotype

4

Proband

The particular person being reported on

5

Polymerase Chain Reaction

Molecular biology lab technique used to amplify DNA

1) Denaturation= DNA is denatured by heating to make two separate strands
2) Annealing= premade primers/ oligonucleotides anneal to a specific sequence on each strand to be amplified
3) Elongation= heat stable DNA polymerase replicates the DNA between the primers

6

Mnemonic for Bolts

SNoW DRoP

Southern= DNA
Northern= RNA
Western= Protein

7

Southwestern Blot

Identifies DNA-binding proteins

8

Microarrays

- Thousands of nucleic acid sequences are arranged in grids on glass or silicon i.e. "chip"
- DNA or RNA probes are hybridized to the chip
- Scanner detects complimentary binding
- Used to detect SNPs or CNV

9

ELISA

Used to detect the presence of either a specific antigen (direct/ sandwich) or antibody (indirect) in a patient's blood

10

Direct/ Sandwich ELISA

- Uses a test antibody to see if a specific antigen is present in the patient's blood
- A second antibody is coupled to a color-generating enzyme to detect the antigen/primary antibody

11

Indirect ELISA

- Uses a test antigen so see if a specific antibody is present in the patient's blood
- A secondary antibody coupled to a color-generating enzyme is added to detect the first antibody

12

FISH

- Fluorescent DNA or RNA probe binds to a specific gene site of interest on a chromosome
- Used for localization of genes & direct visualization of anomalies (micodeletions)
- Fluoresce= gene present, No Fluoresce= NOT present

13

Karyotyping

- Process in which metaphase chromosomes are stained, ordered, & numbered according to morphology, size, arm-length, and banding pattern.
- Can be performed on blood, bone marrow, amniotic fluid, or placental tissue.
- Used to diagnose chromosome imbalances

14

Codominance

- Both alleles contribute to the phenotype of the heterozygote
- E.g. Blood groups

15

Variable Expressivity

- Phenotype varies among individuals with the same genotype
- E.g. NF-1

16

Incomplete penetrance

- Not all individuals with mutant genotype show the mutant phenotype
- E.g. BRCA1 gene mutations do not always result in breast or ovarian cancer

17

Pleiotropy

- One gene contributes to multiple phenotypic effects

18

Anticipation

- Increased severity or earlier onset of disease in succeeding generations
- Trinucleotide repeat disorders (Huntington's Disease)

19

Loss of Heterozygosity

- Patient inherits or develops a mutation in a tumor suppressor gene; the complementary allele must be deleted/mutated before cancer develops
- NOT true of oncogenes
- E.g. Retinoblastoma (Two-Hit Model)

20

Dominant Negative Mutation

- Exerts a dominant effect. A heterozygote produces a nonfunctional altered protein that also prevents the normal gene product from functioning.
- Collagen proteins

21

Linkage Disequilibrium

- Tendency for certain alleles at 2 linked loci to occur together more often than expected by chance in a population

22

Mosaicism

- Presence of genetically distinct cell lines in the same individual. Arises from mitotic errors after fertilization.
- Somatic mosaicism= mutation propagates through multiple tissues or organs
- Gonadal= mutation only in egg or sperm cells

23

Uniparental Disomy

- Offspring receives 2 copies of a chromosome from 1 parent & no copies from the other
- Uniparental is eUploid (normal #, not aneuploid)
- Consider in an individual manifesting a recessive disorder when only one parent is a carrier

24

Hardy-Weinberg Equation

p^2 + 2pq + q^2= 1

25

Hardy-Weinberg Assumptions

- No mutation occurring at the locus
- Natural selection not occurring
- Completely random mating
- No net migration

26

Imprinting

- At some loci, only one allele is active
- The alternate allele is inactivated by methylation, or "imprinted"
- Disease results when there is a mutation or deletion of the active gene

27

Prader-Willi Syndrome

-Paternal gene is deleted/ mutated (chromosome 15)
- Results in hyperphagia, obesity, intellectual disability, hypogonadism, & hypotonia

28

AngelMan Syndrome

- Maternal gene is deleted/mutation (chromosome 15)
- Results in inappropriate laughter, seizures, ataxia, & severe intellectual disability

29

Autosomal Dominant Inheritance

- Often due to defects in structural genes (but also signaling, growth differentiation, & development)
- Many generations affected
- Both males & females affected

30

Autosomal Recessive Inheritance

- 25% of offspring from 2 carrier parents are affected
- Often enzyme deficiencies
- Usually seen in only one generation
- Increased risk with consanguineous families

31

X-Linked Dominant Inheritance

- Transmitted through both parents
- Mothers transmit to 50% of daughters
- Fathers transmit to all daughters but NO sons

32

X-Linked Recessive Inheritance

- No male-to-male transmission
- Sons of heterozygous mothers have a 50% chance of being affected
- Commonly more severe in males

33

Mitochondrial Inheritance

- Transmitted only through the mother
- All offspring of affected females may show signs of disease